X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTransforms%2FUtils%2FLowerSwitch.cpp;h=d75880f585c3b3e7941a52e73518f52d09b93372;hp=0ba37c275bbe91fddcf24debf94a6e263b9a337a;hb=051a950000e21935165db56695e35bade668193b;hpb=fd93908ae8b9684fe71c239e3c6cfe13ff6a2663 diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp index 0ba37c275bb..d75880f585c 100644 --- a/lib/Transforms/Utils/LowerSwitch.cpp +++ b/lib/Transforms/Utils/LowerSwitch.cpp @@ -2,63 +2,89 @@ // // The LLVM Compiler Infrastructure // -// This file was developed by the LLVM research group and is distributed under -// the University of Illinois Open Source License. See LICENSE.TXT for details. +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // -// The LowerSwitch transformation rewrites switch statements with a sequence of -// branches, which allows targets to get away with not implementing the switch -// statement until it is convenient. +// The LowerSwitch transformation rewrites switch instructions with a sequence +// of branches, which allows targets to get away with not implementing the +// switch instruction until it is convenient. // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Scalar.h" +#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h" #include "llvm/Constants.h" #include "llvm/Function.h" #include "llvm/Instructions.h" #include "llvm/Pass.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/Support/Debug.h" -#include "llvm/ADT/Statistic.h" +#include "llvm/Support/Compiler.h" #include using namespace llvm; namespace { - Statistic<> NumLowered("lowerswitch", "Number of SwitchInst's replaced"); - /// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch /// instructions. Note that this cannot be a BasicBlock pass because it /// modifies the CFG! - class LowerSwitch : public FunctionPass { + class VISIBILITY_HIDDEN LowerSwitch : public FunctionPass { public: - bool runOnFunction(Function &F); - typedef std::pair Case; - typedef std::vector::iterator CaseItr; + static char ID; // Pass identification, replacement for typeid + LowerSwitch() : FunctionPass((intptr_t) &ID) {} + + virtual bool runOnFunction(Function &F); + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + // This is a cluster of orthogonal Transforms + AU.addPreserved(); + AU.addPreservedID(PromoteMemoryToRegisterID); + AU.addPreservedID(LowerInvokePassID); + AU.addPreservedID(LowerAllocationsID); + } + + struct CaseRange { + Constant* Low; + Constant* High; + BasicBlock* BB; + + CaseRange() : Low(0), High(0), BB(0) { } + CaseRange(Constant* low, Constant* high, BasicBlock* bb) : + Low(low), High(high), BB(bb) { } + }; + + typedef std::vector CaseVector; + typedef std::vector::iterator CaseItr; private: void processSwitchInst(SwitchInst *SI); BasicBlock* switchConvert(CaseItr Begin, CaseItr End, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default); - BasicBlock* newLeafBlock(Case& Leaf, Value* Val, + BasicBlock* newLeafBlock(CaseRange& Leaf, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default); + unsigned Clusterify(CaseVector& Cases, SwitchInst *SI); }; /// The comparison function for sorting the switch case values in the vector. + /// WARNING: Case ranges should be disjoint! struct CaseCmp { - bool operator () (const LowerSwitch::Case& C1, - const LowerSwitch::Case& C2) { - if (const ConstantUInt* U1 = dyn_cast(C1.first)) - return U1->getValue() < cast(C2.first)->getValue(); + bool operator () (const LowerSwitch::CaseRange& C1, + const LowerSwitch::CaseRange& C2) { - const ConstantSInt* S1 = dyn_cast(C1.first); - return S1->getValue() < cast(C2.first)->getValue(); + const ConstantInt* CI1 = cast(C1.Low); + const ConstantInt* CI2 = cast(C2.High); + return CI1->getValue().slt(CI2->getValue()); } }; - RegisterOpt + char LowerSwitch::ID = 0; + RegisterPass X("lowerswitch", "Lower SwitchInst's to branches"); } +// Publically exposed interface to pass... +const PassInfo *llvm::LowerSwitchID = X.getPassInfo(); // createLowerSwitchPass - Interface to this file... FunctionPass *llvm::createLowerSwitchPass() { return new LowerSwitch(); @@ -81,19 +107,24 @@ bool LowerSwitch::runOnFunction(Function &F) { // operator<< - Used for debugging purposes. // -std::ostream& operator<<(std::ostream &O, - const std::vector &C) { +static std::ostream& operator<<(std::ostream &O, + const LowerSwitch::CaseVector &C) { O << "["; - for (std::vector::const_iterator B = C.begin(), + for (LowerSwitch::CaseVector::const_iterator B = C.begin(), E = C.end(); B != E; ) { - O << *B->first; + O << *B->Low << " -" << *B->High; if (++B != E) O << ", "; } return O << "]"; } +static OStream& operator<<(OStream &O, const LowerSwitch::CaseVector &C) { + if (O.stream()) *O.stream() << C; + return O; +} + // switchConvert - Convert the switch statement into a binary lookup of // the case values. The function recursively builds this tree. // @@ -107,15 +138,17 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, return newLeafBlock(*Begin, Val, OrigBlock, Default); unsigned Mid = Size / 2; - std::vector LHS(Begin, Begin + Mid); - DEBUG(std::cerr << "LHS: " << LHS << "\n"); - std::vector RHS(Begin + Mid, End); - DEBUG(std::cerr << "RHS: " << RHS << "\n"); - - Case& Pivot = *(Begin + Mid); - DEBUG(std::cerr << "Pivot ==> " - << (int64_t)cast(Pivot.first)->getRawValue() - << "\n"); + std::vector LHS(Begin, Begin + Mid); + DOUT << "LHS: " << LHS << "\n"; + std::vector RHS(Begin + Mid, End); + DOUT << "RHS: " << RHS << "\n"; + + CaseRange& Pivot = *(Begin + Mid); + DEBUG( DOUT << "Pivot ==> " + << cast(Pivot.Low)->getValue().toStringSigned(10) + << " -" + << cast(Pivot.High)->getValue().toStringSigned(10) + << "\n"); BasicBlock* LBranch = switchConvert(LHS.begin(), LHS.end(), Val, OrigBlock, Default); @@ -125,13 +158,13 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, // Create a new node that checks if the value is < pivot. Go to the // left branch if it is and right branch if not. Function* F = OrigBlock->getParent(); - BasicBlock* NewNode = new BasicBlock("NodeBlock"); - F->getBasicBlockList().insert(OrigBlock->getNext(), NewNode); + BasicBlock* NewNode = BasicBlock::Create("NodeBlock"); + Function::iterator FI = OrigBlock; + F->getBasicBlockList().insert(++FI, NewNode); - SetCondInst* Comp = new SetCondInst(Instruction::SetLT, Val, Pivot.first, - "Pivot"); + ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT, Val, Pivot.Low, "Pivot"); NewNode->getInstList().push_back(Comp); - new BranchInst(LBranch, RBranch, Comp, NewNode); + BranchInst::Create(LBranch, RBranch, Comp, NewNode); return NewNode; } @@ -141,27 +174,58 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, // can't be another valid case value, so the jump to the "default" branch // is warranted. // -BasicBlock* LowerSwitch::newLeafBlock(Case& Leaf, Value* Val, +BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default) { Function* F = OrigBlock->getParent(); - BasicBlock* NewLeaf = new BasicBlock("LeafBlock"); - F->getBasicBlockList().insert(OrigBlock->getNext(), NewLeaf); - - // Make the seteq instruction... - SetCondInst* Comp = new SetCondInst(Instruction::SetEQ, Val, - Leaf.first, "SwitchLeaf"); - NewLeaf->getInstList().push_back(Comp); + BasicBlock* NewLeaf = BasicBlock::Create("LeafBlock"); + Function::iterator FI = OrigBlock; + F->getBasicBlockList().insert(++FI, NewLeaf); + + // Emit comparison + ICmpInst* Comp = NULL; + if (Leaf.Low == Leaf.High) { + // Make the seteq instruction... + Comp = new ICmpInst(ICmpInst::ICMP_EQ, Val, Leaf.Low, + "SwitchLeaf", NewLeaf); + } else { + // Make range comparison + if (cast(Leaf.Low)->isMinValue(true /*isSigned*/)) { + // Val >= Min && Val <= Hi --> Val <= Hi + Comp = new ICmpInst(ICmpInst::ICMP_SLE, Val, Leaf.High, + "SwitchLeaf", NewLeaf); + } else if (cast(Leaf.Low)->isZero()) { + // Val >= 0 && Val <= Hi --> Val <=u Hi + Comp = new ICmpInst(ICmpInst::ICMP_ULE, Val, Leaf.High, + "SwitchLeaf", NewLeaf); + } else { + // Emit V-Lo <=u Hi-Lo + Constant* NegLo = ConstantExpr::getNeg(Leaf.Low); + Instruction* Add = BinaryOperator::createAdd(Val, NegLo, + Val->getName()+".off", + NewLeaf); + Constant *UpperBound = ConstantExpr::getAdd(NegLo, Leaf.High); + Comp = new ICmpInst(ICmpInst::ICMP_ULE, Add, UpperBound, + "SwitchLeaf", NewLeaf); + } + } // Make the conditional branch... - BasicBlock* Succ = Leaf.second; - new BranchInst(Succ, Default, Comp, NewLeaf); + BasicBlock* Succ = Leaf.BB; + BranchInst::Create(Succ, Default, Comp, NewLeaf); // If there were any PHI nodes in this successor, rewrite one entry // from OrigBlock to come from NewLeaf. for (BasicBlock::iterator I = Succ->begin(); isa(I); ++I) { PHINode* PN = cast(I); + // Remove all but one incoming entries from the cluster + uint64_t Range = cast(Leaf.High)->getSExtValue() - + cast(Leaf.Low)->getSExtValue(); + for (uint64_t j = 0; j < Range; ++j) { + PN->removeIncomingValue(OrigBlock); + } + int BlockIdx = PN->getBasicBlockIndex(OrigBlock); assert(BlockIdx != -1 && "Switch didn't go to this successor??"); PN->setIncomingBlock((unsigned)BlockIdx, NewLeaf); @@ -170,6 +234,44 @@ BasicBlock* LowerSwitch::newLeafBlock(Case& Leaf, Value* Val, return NewLeaf; } +// Clusterify - Transform simple list of Cases into list of CaseRange's +unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) { + unsigned numCmps = 0; + + // Start with "simple" cases + for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) + Cases.push_back(CaseRange(SI->getSuccessorValue(i), + SI->getSuccessorValue(i), + SI->getSuccessor(i))); + std::sort(Cases.begin(), Cases.end(), CaseCmp()); + + // Merge case into clusters + if (Cases.size()>=2) + for (CaseItr I=Cases.begin(), J=next(Cases.begin()); J!=Cases.end(); ) { + int64_t nextValue = cast(J->Low)->getSExtValue(); + int64_t currentValue = cast(I->High)->getSExtValue(); + BasicBlock* nextBB = J->BB; + BasicBlock* currentBB = I->BB; + + // If the two neighboring cases go to the same destination, merge them + // into a single case. + if ((nextValue-currentValue==1) && (currentBB == nextBB)) { + I->High = J->High; + J = Cases.erase(J); + } else { + I = J++; + } + } + + for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) { + if (I->Low != I->High) + // A range counts double, since it requires two compares. + ++numCmps; + } + + return numCmps; +} + // processSwitchInst - Replace the specified switch instruction with a sequence // of chained if-then insts in a balanced binary search. // @@ -182,17 +284,17 @@ void LowerSwitch::processSwitchInst(SwitchInst *SI) { // If there is only the default destination, don't bother with the code below. if (SI->getNumOperands() == 2) { - new BranchInst(SI->getDefaultDest(), CurBlock); + BranchInst::Create(SI->getDefaultDest(), CurBlock); CurBlock->getInstList().erase(SI); return; } // Create a new, empty default block so that the new hierarchy of // if-then statements go to this and the PHI nodes are happy. - BasicBlock* NewDefault = new BasicBlock("NewDefault"); + BasicBlock* NewDefault = BasicBlock::Create("NewDefault"); F->getBasicBlockList().insert(Default, NewDefault); - new BranchInst(Default, NewDefault); + BranchInst::Create(Default, NewDefault); // If there is an entry in any PHI nodes for the default edge, make sure // to update them as well. @@ -203,19 +305,19 @@ void LowerSwitch::processSwitchInst(SwitchInst *SI) { PN->setIncomingBlock((unsigned)BlockIdx, NewDefault); } - std::vector Cases; + // Prepare cases vector. + CaseVector Cases; + unsigned numCmps = Clusterify(Cases, SI); - // Expand comparisons for all of the non-default cases... - for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) - Cases.push_back(Case(SI->getSuccessorValue(i), SI->getSuccessor(i))); - - std::sort(Cases.begin(), Cases.end(), CaseCmp()); - DEBUG(std::cerr << "Cases: " << Cases << "\n"); + DOUT << "Clusterify finished. Total clusters: " << Cases.size() + << ". Total compares: " << numCmps << "\n"; + DOUT << "Cases: " << Cases << "\n"; + BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val, OrigBlock, NewDefault); // Branch to our shiny new if-then stuff... - new BranchInst(SwitchBlock, OrigBlock); + BranchInst::Create(SwitchBlock, OrigBlock); // We are now done with the switch instruction, delete it. CurBlock->getInstList().erase(SI);